Dental drill chuck



July 21, 1959 BAKER 2,895,738

DENTAL DRILL CHUCK Filed Sept. 22, 1958 fl/A 42 1 /2 & 4 I I Z 5 z a ij- I a l I z INVENTOR. R0361? M Baker BY A TTURNE Y5 United StatesPatent DENTAL DRILL CHUCK Robert N. Baker, Kings Mountain, N.C.,assignor to Bowen & Company, Inc., Rockville, Md., a corporation ofDelaware Application September 22, 1958, Serial No. 762,536

8 Claims. (Cl. 279-1) This invention relates to dental drills, andparticularly to dental drills wherein a tool is mounted on and driven bya high speed fluid turbine. It is to be understood, however, that theinvention may be employed in rotary K1018 other than those designedespecially for dental Work.

In previous dental tools of this type, difliculty and inconvenience wereencountered in mounting and removing dilferent tools from the turbinebecause the turbine was enclosed in a housing and most tools werethreadedly engaged with holding means on the turbine Shaft. To mount orremove such tools it was necessary to employ a wrench or similarinstrumentality to hold the turbine stationary while the tool wasmounted or removed.

According to the present invention means are provided whereby a tool maybe readily removed from threaded engagement with such turbine by merelyapplying manual pressure to a portion of the turbine housing. Theturbine shaft is hollow and provided at one end with a conical surfacefor frictionally engaging a portion of the tool, the shaft of which isthreadedly engaged with a member slidable in the hollow shaft. Theslidable memher is resiliently urged in a direction to frictionallyengage the tool shank with the conical surface but can be moved in theother direction to disengage the tool shank from the conical surface byapplying manual pressure to a projecting end of the slidable member. Theprojecting end is covered by a. resilient diaphragm fixed to the turbinehousing so that the application of manual pressure thereto not onlymoves the tool axially out of frictional engagement with the .conicalsurface but also holds the slidable member against rotation so that thetool may then be readily unscrewed therefrom.

It is therefore an object of this invention to provide holding means fora dental tool driven by a high speed fluid turbine wherein no specialtools are required for mounting or demounting the tool.

Another .object of the invention is to provide a dental tool mountingincluding a friction drive and means for readily releasing the tool fromfrictional engagement with its driving means.

Still another object of the invention is to provide a dental tool of thetype described wherein the tool is threadedly engaged with its holdingmeans.

A further object is to provide manually operable means adapted to hold atool driving member stationary and release a frictional connectionbetween a high speed fluid turbine and a dental tool.

A still further object is to provide a device of the type set forthwherein the manually operable means are completely sealed with respectto the turbine housing.

Other and additional objects and advantages will become apparent tothose skilled in the art as the description proceeds in connection withthe accompanying drawings, wherein:

Fig. 1 is an enlarged sectional view of a dental drill embodying thepresent invention; and

Fig. 2 is a view similar to Fig. 1 but showing the parts in differentrelative positions.

The improvement of the present invention is shown, by way of examples,as applied to a high speed fluid driven turbine device which may beemployed to drive dental drills or other dental tools. A hollow handle 2is provided with a hollow enlargement 4 at .one end thereof defining ahousing for the turbine. A nozzle 5 directs fluid under pressure towardthe turbine blades and spent fluid returns in hollow handle 2. Theturbine comprises a rotor shaft portion 6 having turbine blades 8 fixedthereon. The shaft portion 6 is journalled in bearings 10 and 12, heldin the housing 4 by suitable fittings 14 and 16 threaded into oppositesides of the housing 4. The bearings 10 and 12 are open-ended and therotor shaft 6 projects from opposite ends of the housing 4, as shown.

The rotor shaft 6 is provided with a central axial bore 18 therethroughand the bore 18 is formed at one end with an outwardly diverging conicalsurface 20. Axially slidable within the bore 18 is a holding member 22.The member 22 fits bore 18 fairly snugly but is freely slidable thereinin an axial direction and is provided with an internally threaded bore24 from the end thereof adjacent the flared surface 20. The holdingmember 22 extends outwardly of the bore 18 from the end opposite theflared portion 20 and is provided with an integral enlarged head 26joined to the body portion by a reduced neck 28. A rubber or the likeO-ring 30 surrounds the neck 28 and bears against the under surface ofhead 26 and the left end of rotor shaft 6. Thus, the O-ring 30resiliently urges the holding member 22 toward the left as seen in Fig.1, at least to the position shown in that figure.

The fitting 16 extends outwardly of the bearing 12 and is provided withan internal circumferential groove 32. A cap-shaped resilient diaphragm34 of rubber or similar material is provided with a peripheral flange 36extending into the groove 32. As shown, the cap diaphragm 34 extendsover and covers the head 26 and its flange 36 constitutes a sealingmeans whereby the space within the cap 34 is effectively sealed from theexterior of the turbine housing.

The structure thus far described is adapted to hold a dental toolindicated generally at 38, which may be provided with any suitablecutting burr, abrading wheel, brush, or the like. The tool 38 isprovided with a shank having a threaded end portion 40 adapted to bethreadedly engaged in the threaded bore 24 of holding member 22. Thetool shank is also provided with a tapered conical surface 42complementary to the flared portion 20 of bore 18 whereby tofrictionally engage the portion 20 to be frictionally driven thereby.

Assuming that a tool 38 is mounted in the device, as illustrated in Fig.1, it will be obvious that resilience of the O-ring 30 firmly holds thetapered surface 42 in frictional driving engagement with the flaredportion 20 of bore 18 and thus rotation of the turbine shaft 6 effectsrotation of the tool 38 therewith. When it is desired to remove the tool38, pressure is applied to the outer surface of the cap diaphragm 34, asindicated by the arrow A of Fig. 2. While the cap diaphragm 34 is shownin Fig. l as being normally spaced from the head 26, when pressure isapplied thereto as indicated in Fig. 2, the cap diaphragm is distortedand depressed into frictional engagement with the outer surface of thehead 26. Continued inward pressure on the diaphragm 34 forces the head26, neck 28, holding member 22, and tool 38 to the right whilecompressing O-ring 30 in the manner shown. Movement of the parts to theright as described and as shown in Fig. 2, results in disengage ment ofthe tapered surface 42 of tool 38 from the flared surface 20 of bore 18and the tool 38 is thus free from driving engagement with the shaft 6.In this condition the tool may be manually grasped and unscrewed fromthe threaded bore 24. At the same time it is to be noted that thediaphragm 34, being secured to the tur-. bine housing, does not rotateand frictionally engages head 26 to hold the latter and holding member22 against rotation. By thus holding member 22 against rotation, thetool 38 may be easily unscrewed from the holding member while merelyapplying pressure to the diaphragm 34 and without the use of any specialholding tools. Obviously the procedure may be reversed in mounting atool 38 on the turbine. When it is desired to mount a tool it is onlynecessary to depress diaphragm 34 to the position of Fig. 2, whereupon'a tool 38 may be threaded into holding member 22 until its taperedsurface closely approaches the flared portion 20 of rotor shaft 6. Then,upon release of diaphragm 34, O-ring 30 urges the part to the left andto the position of Fig. 1 wherein the tapered surface 42 is held in firmfrictional driving engagement with the flared end of the bore 18.

The bearings and 12 necessarily support the turbine rotor rather looselyand some fluid leakage may occur past those bearings. The cap diaphragm34 prevents any fluid leaking past the bearing 12 from escaping to theexterior of the apparatus. Likewise, O-ring 30 sealingly engages theinner surface of head 26 and the end face of rotor shaft 6 to therebyseal the bore 18 against entry of any fluid leaking past the bearing 12.Turbines of the type described are often driven by water under pressureand if such water were to leak past bearing 12 and enter the clearancebetween holding member 22 and bore 18, corrosion or other fouling couldoccur which would hamper the intended mode of operation of the toolholding means. Thus, O-ring 30 performs a dual function.

While a single specific embodiment of the invention is shown anddescribed herein, it is to be understood that other modifications may beresorted to within the scope of the appended claims.

I claim:

1. In a rotary tool having a housing and a fluid driven turbine rotortherein; said turbine rotor having a shaft journalled in said housingand extending through opposite sides thereof, a bore extending axiallythrough said shaft, one end of said bore being flared outwardly, holdingmeans slidable in said bore for holding an end of a tool, and meansresiliently urging said holding means away from said flared end andtoward the other end of said bore whereby to frictionally hold acomplementary portion of the tool against said flared portion of saidbore.

2. A rotary tool as defined in claim 1 wherein a portion of said holdingmeans projects outwardly from the other end of said bore to providemeans for manually moving said holding means against the action of saidresilient means for releasing said portion of said tool 4 fromfrictional engagement with said flared portion of said bore.

3. A rotary tool as defined in claim 2 wherein said holding means isprovided with a threaded portion for threadedly holding said end of saidtool, and a resilient diaphragm secured to said housing and overlyingsaid projecting end of said holding means whereby axially inward manualpressure on said diaphragm moves said holding means to release said toolfrom said frictional engagement and also holds said holding meansagainst rotation relative to said housing for unscrewing said tooltherefrom.

4. In a rotary tool having a housing and a fluid driven turbine rotortherein; said turbine rotor having portions journalled in said housingand extending through opposite sides thereof, means carried by one ofsaid portions for threadedly receiving and holding a tool to projectfrom one end of said rotor, and axially movable friction means securedto said housing and overlying the other of said portions in normallyspaced relation thereto whereby axially inward manual pressure on saidfriction means moves the same into frictional engagement with said otherportion to thereby hold said rotor against rotation.

5. A rotary tool as defined in claim 4 wherein said friction meanscomprises a resilient cap overlying said other portion and sealinglysecured to said housing throughout its periphery.

6. In a rotary tool having a housing and a fluid driven turbine rotortherein; said turbine rotor having a shaft journalled in said housingand extending through opposite sides thereof, a bore extending axiallythrough said shaft, one end of said bore being flared outwardly, aholding member slidable in said bore and having a threaded portionadjacent said flared end for threadedly engaging an end of a tool, saidholding member projecting outwardly of the other end of said bore andhaving a radially enlarged head thereon, and resilient means betweensaid head and the adjacent end of said shaft urging said memberoutwardly of said other end of said bore whereby to releasably hold aportion of the tool in firm frictional engagement with said flaredportion of said bore.

7. A rotary tool as defined in claim 6 wherein said resilient means isan O-ring surrounding said member inwardly of said head and sealinglyengaging said head and shaft.

8. A rotary tool as defined in claim 6 including a resilient cap-likediaphragm secured to said housing and overlying said head in normallyspaced relation thereto but manually depressable to engage said head andmove said member inwardly of said bore while frictionally holding saidmember against rotation.

References Cited in the file of this patent UNITED STATES PATENTS

